Pan-African ages from a Tibesti Massif batholith, southern Lybia
Abstract
The northwestern portion of the Tibesti Massif in south-central Libya consists of a complex granitic batholith (the Ben Ghnema batholith) surrounded by medium- to low-grade metamorphic wall rocks. Rb-Sr whole-rock analyses of a suite of calc-alkaline rocks from the batholith give an age of about 560 m.y. and an initial 87Sr/ 86Sr ratio of about 0.706. This age is within the accepted range of the Pan-African orogeny which caused extensive plutonism throughout much of northwestern Africa. The relatively low initial ratio suggests that the magma was derived in the lower crust-upper mantle region and perhaps experienced some degree of mixing with older sialic material.
- Publication:
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Earth and Planetary Science Letters
- Pub Date:
- April 1976
- DOI:
- 10.1016/0012-821X(76)90014-5
- Bibcode:
- 1976E&PSL..30..123P